Is this a standard procedure, getting a model release form when trading products for photos?

It is absolutely illegal to use or reproduce a photographers photos in any form unless you have permission from the photographer. Dealing with the photographer directly is always the better choice unless you deal with a model who can provide you with a release form from their photographer that they use. Your rights when you get photos done are limited to having the prints that you order, unless otherwise stated by the photographer. You can't post them online without permission, you can't duplicate them without permission, normally you have to order prints directly from the photographer, etc... If they give out cds, its possible that they allow photos to be posted online or prints made personally but its always best to check with the photographer first. There are heavy fines for illegally using a pro's photos without the proper permissions.